Storm-chaser aiming for eye of Cyclone Debbie

US-BASED storm-chaser Josh Morgerman has warned that Cyclone Debbie is shaping up to look like a "worst case scenario" for Queensland as it approaches landfall.

The self-described "hardcore hurricane chaser" jetted into Brisbane from California on Monday and headed to Emerald and Proserpine before bunkering down in Bowen, where he is hoping to feel the eye wall of the storm.

He told news.com.au the cyclone looked like "garbage all day" but became extremely symmetrical and circular on Monday afternoon - a sign it was growing in intensity.

"The more symmetrical and perfectly rounded, the more intense it is," he said.

"That's a worst-case scenario, storms that are rapidly strengthening as they approach the coast … That's a real concern and I am worried about the impact.

"A steady-state storm or a weakening one is better than one that's intensifying as they approach the coast."